Improvement in processes of separating gold and silver from lead



- Y 2. S'heers-- sheef.1.f D. P. WEBSTER, C. C. LEWISl & A. ,P FWE'BSTER. Processes of'Separating Gold and Silver From Lead.

No.l53,l36. PafentedJulyMJaM.

2 Sheets--Sheet 2.

WEBSTER.

Patented July 14, 1874.

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o. P. WEBSTER, eye. Lowers oA. P. Processes of Separating Gold and Silver From Lead.

UNITED STATES PATENT FFICE.

yDAVID I). WEBSTER, CHARLES c. LEWIS, AND ALMAR r. WEBSTER, 0E NEW YORK, N. Y.

IMPROVEMENT lN PROCESSESDF SEPARATING GOLD AND SILVER FROM LEAD.

Specification forming partof Letters Patent N o. 153,136, dated July 14, 1874; application filed July 3, 1874.

OASE B.

To all whom 'it may concern:

Be it known thatwe, DAVID P. WEBSTER, CHARLES C. LEWIS, and ALMAR RWEBSTER, of New York, county and State of New York, have invented certain new and useful Improvements inthe Arts of Separating Gold and Silver from Lead, of which the following is a specification By our improvements we are enabled to desilver lead and extract gold from the same, with less labor in handling the metal, less fuel, and the use of less metallic Zinc than has been heretofore required to effect the same result, and which process is an improvement of the process described in theLetters Patent granted to us by the United States, bearing date of February l0, 1874, and numbered 147,454.

In this improvement we are enabled to diS- pense with the use of the furnace represented by Fig. l in the drawing accompanying and forming part of the specification of that patent, and perform all the work in the retort and furnace represented in the same patent above referred to by the Figs. 3, 4, and 5, and shown in Figs. 1,2, and 3, reproduced in the drawings accompanying and forming part of this specification.

Figure l is a longitudinal section of the furnace, showing the retort a and the angle at which it is set. The arch d, Figs. l and 2, serves to shield the retort from the direct action of the flame. The small flues h h admit the liame and heat above the arch, and are located at the four corners of the furnace. The fire-box is indicated byfin both figures, and the ash-pit by g.

The retort is made, preferably, of cast-iron, in the shape of a bottle, having attached to and cast with it, at its bottom, two pipes, as shown atb b, Fig. l. The body of the retort is cylindrical, two feet diameter outside, and two feet nine inches long between the points where the contraction is commenced. The mouth or neck is nineteen inches long and eleven in diameter. The pipes at the bottom are fourteen inches long each, and four and one-half outside diameter, making the whole length five and one-half feet. The uniform thickness of the metal is one inch.

Fig. 2 is a cross-section of the furnace, in

which the arch is more plainly shown at d than it is iu Fig. l. The furnace isv built of rebrick, stayed, and braced by iron bands and rods, as is usual in the construction of like furnaces.

Fig. 3 is a perspective view of the furnace, showing the mouth end ofthe retort and part of the kettle at the opposite end C, for collecting the melted metal when allowed to run from the retort. The outside dimensions of this furnace are tive feet ten inches long, ve feet wide, and four feet ten inches high. The walls are nine inches thick. The retort within the furnace rests upon piers of fire-brick built upon the arch. The two necks or pipes at the lower end of the retort are provided, so that when the one on the side placed nearest the fire becomes defective it may be turned uppermost, and thus the retort is made to last much longer than if only one pipe were provided. The upper pipe is always kept closed.

The process for extracting the gold or silver from lead is proceeded with and practiced as follows: For example, if the lead to be operated upon contains two hundred ounces of silver to the ton, (2000 pounds,) We first place one hundred pounds of metallic zinc, in lumps of various sizes, in the retort. On top ofthe zinc we place two thousand pounds of lead bullion in the form of pigs7 The mouth'of the retort is then closed, and the heat elevated until the retort has reached a dull-red heat. It is then opened and the mass well stirred or mixed by an iron hoe during about ten minutes. The retort is again closed, and allowed torest about fifteen minutes, when the operation is repeated twice, and the mass left standing about twenty minutes. The lead is then drawn off by opening the lower pipe into the kettle c, when the pipe is closed. The dross from the surface of the melted metal in the kettle is next skimmed oif and placed in the retort. One thousand pounds of lead bullion are then placed in the retort without the addition of zinc, and stirred and drawn off precisely as described above. The skimmings or dross from the kettle are again added to the retort, and fty pounds of zinc also added to placed in the retort, as before.

the contents of the retort; then one thousand pounds of lead bullion are placed on top of the Whole, the stirring and intervals above described repeated, and the metal drawn oif to the kettle. The skimming of the metal in the kettle is again repeated, and the ,dross Fifty pounds of zinc are `next placed in the retort, and one thousand pounds of lead bullion added, with the stirring and intervals, as in the other charges, repeated. We next place seventy pounds of zinc in the retort and one thousand pounds of lead bullion, and treat as before. One thousand pounds of lead bullion are next placed in the retort, Without the addition of zinc, and treated as the previous batches were treated. The last charge of one thousand pounds of lead bullion is repeated twice, making in all nine thousand pounds of lead bullion treated. This completes what We technically term one operation.

The silver or gold originally contained in the lead bullion remains now in the dross With in the retort. This dross is removed and placed on an iron plate, and while hot stirred, in order to granulate it, and prevent it from congealing into a solid mass. This granulated dross is removed and placed in a plumbago or clay retort, and the zinc distilled off. The residuum left in the retort is cast into ingots, which are placed on the cupel in the cupel-fur ofJunc, 1874.

nace, and treated' as usual in the process of cupelation.

Having thus described our improvement, what We claim, and desire to secure by Letters Patent, is-

1. The process of treating lead bullion for` separating gold or silver, by means of zinc in a closed retort, substantially as herein described.

2. The treatment of lead bullion containing silver or gold, by successive additions of zinc in a closed retort, substantially as described.

3. The treatment of lead bullion containing silver or gold, by means of zinc, in a chamber in which the air is so highly rariied that it has little or no oxidizing effect upon the zinc, substantially as described.

4i. The process of separating gold and silver from lead, consisting in treating crude bullion With zinc, and returning the skimmings to the retort with successive additions of fresh bullion and zinc, substantially as specified.

In testimony that We claim the foregoing We have hereunto set our hands this 29th day DAVID P. WEBSTER. CHARLES C. LEWIS. ALMAR I. WEBSTER.

Titnesses J. O. NoXoN, l). .1). PARMELEE. 

